AT89S8253-24AC Atmel, AT89S8253-24AC Datasheet - Page 11

• Manufacturer Part Number: AT89S8253-24AC
• Description: IC 8051 MCU FLASH 12K 44TQFP
• Manufacturer: Atmel
• Series: 89Sr

Specifications of AT89S8253-24AC

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 24MHz
• Connectivity: SPI, UART/USART
• Peripherals: POR, WDT
• Number Of I /o: 32
• Program Memory Size: 12KB (12K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 2K x 8
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 44-TQFP, 44-VQFP
• Data Bus Width: 8 bit
• Data Ram Size: 256 B
• Interface Type: SPI, UART
• Maximum Clock Frequency: 24 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 3 bit
• Operating Supply Voltage: 2.7 V to 5.5 V
• Maximum Operating Temperature: + 70 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: 0 C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Data Converters: -
• Lead Free Status / Rohs Status: No

7. Power-On Reset
Figure 7-1.
7.1
3286P–MICRO–3/10
Min V
Memory Brown-out Protection
BOD Level 2.3V
POR Level 1.4V
CC
WRTINH
Level 2.7V
Internal
RESET
XTAL1
Power-up and Brown-out Detection Sequence
POR
V
0
CC
A Power-On Reset (POR) is generated by an on-chip detection circuit. The detection level is
nominally 1.4V. The POR is activated whenever V
cuit can be used to trigger the start-up reset or to detect a supply voltage failure in devices
without a brown-out detector. The POR circuit ensures that the device is reset from power-on.
When V
how long the device is kept in POR after V
again, without any delay, when V
a cold reset) will set the POF flag in PCON.
The AT89S8253 has an on-chip Brown-out Detection (BOD) circuit for monitoring the V
during operation by comparing it to a fixed trigger level of nominally 2.2V (2.4V max). The pur-
pose of the BOD is to ensure that if V
erased/written at voltages too low for programming. At powerup the V
BOD threshold before execution starts. When V
the WRTINH bit in EECON is activated and futher programming of the Flash/EEPROM is
restricted. When V
ming until after the timeout period has expired in approximately 2 ms. The BOD does not reset
the system as shown in
cution at lower voltages an external BOD circuit may be required.
(2 ms)
t
POR
CC
reaches the Power-on Reset threshold voltage, the POR delay counter determines
2.4V
CC
increases above the trigger level, the BOD delay counter blocks program-
Figure
7-1. To protect the system from errors induced by incorrect exe-
CC
falls below the POR threshold level. A Power-On Reset (i.e.
CC
fails or dips, the Flash or EEPROM memories cannot be
1.2V
CC
rise, nominally 2 ms. The POR signal is activated
CC
CC
decreases to a value below the trigger level,
is below the detection level. The POR cir-
(2 ms)
CC
t
POR
AT89S8253
level must pass the
t
t
t
t
t
CC
level
11